from qiskit import QuantumCircuit
def create_state_prep():
    """ Return a QuantumCircuit that prepares the binary state 1.
    """
    qc = QuantumCircuit(2)
    qc.prepare_state("01")
    return qc

def check(candidate):
    from qiskit.quantum_info import Statevector
    candidate_circuit = candidate()
    assert isinstance(candidate_circuit, QuantumCircuit)
    candidate_sv = Statevector.from_instruction(candidate())
    refrence_sv = Statevector.from_label("1".zfill(candidate_sv.num_qubits))
    assert candidate_sv.equiv(refrence_sv)

    print("OK")

if __name__ == '__main__':
    check(create_state_prep)